This text is intended for all those involved in the investigation of sexual assault crimes and to educate them as to how drugs are used as weapons in committing sexual assaults. Designed as a handbook for all those involved in the investigation and prosecution of drug-assisted sexual assaults, this handbook begins with the history of drug-facilitated crimes and provides an overview of how these crimes have changed over the last decade. The last decade witnessed a dramatic increase in reports about sexual assault victims being knocked out through the use of drugs. The handbook continues with the many challenges that face the investigator of drug-facilitated sexual assault (DFSA). These challenges include: (1) an awareness of the many drugs used to commit DFSA such as ethanol and rohypnol, their effects on the human body, and their pharmacokinetic properties; (2) understanding and acknowledging the complexities of reporting this type of crime; and (3) properly collecting and analyzing the physical evidence. A key element making DFSA difficult to investigate is the drugs used, their effects on the victim, and the difficulty in detecting the presence of the drugs after ingestion. The handbook concludes by providing an outline of ideas and suggestions to overcome the difficulties encountered in DFSA cases.